Carbon Neutral Wiltshire

Notes by Peter Harper, Transcoco March 2019

The Wiltshire County Council has adopted a policy of aiming towards ‘carbon neutrality’ by 2030. My impression is that they are not sure what this means. They appear to assume that ‘carbon-neutrality’ is a single and obvious thing, even if it needs boffins to work out the details.

Unfortunately, it isn’t simple and there are many different understandings, so we have to sift through the various possible meanings, hoping perhaps to find one we can all agree on. Bit like the Brexit shenanigans in the UK parliament!

The take-home message is that if Wiltshire takes responsibility for all the emissions for which it might be considered liable, it is difficult to achieve ‘carbon neutrality’ within the physical space of the county. It would probably have to buy both energy and carbon credits from outside, much as it now does implicitly without having to think about it. Wiltshire’s current gas and electricity supplies come via the gas and electricity grids, while fuel oil comes in tankers from the refineries. Wiltshire receives ‘carbon credits’ from the rest of the world because its emissions enter the shared atmosphere and are not charged for.

But what are the emissions for which the county might be considered responsible? This is a fundamental question that needs to be decided before any plans are made for decarbonisation. There is a series of possible ‘scopes’, nested a bit like Russian dolls, and you have to decide which scope to use.  I’ll list these and give an estimate of the annual emissions of greenhouse gases in thousands of tonnes of CO2 equivalents, or “ktCO2e”. Where the source is energy, I have given the energy demand as well, in gigawatt-hours per year or GWh/y.

  • Scope 0. Just count the emissions produced by the Council itself in delivering its services. I cannot yet find appropriate data for this, but probably it was not what the Council had in mind.
  • Scope 1: Cover the whole county, but just count domestic electricity emissions: 614 GWh/y or 184 ktCO2e at the present level of carbon intensity.     
  • Scope 2. Cover the whole county, but count all emissions from energy consumption in dwellings, that is, electricity and gas plus a bit of fuel oil and wood. A lot more, 3056 GWh/y or 642 ktCO2e, see the two compared in the chart on the right.
  • Scope 3. Whole county, but count all direct energy emissions, dwellings plus transport: more again, 5314 GWh/y, 1397 ktCO2e. These two are compared in the bar chart on the left.
  • Scope 4. Add to the above all other emissions that arise in the territory of the UK, applied to Wiltshire per capita. This includes for example agricultural, industrial, commercial and administrative emissions, from which Wiltshire people benefit and can be deemed responsible for a share pro rata. It’s not all energy. 3244 ktCO2e, comparison in chart on right.
  • Scope 5. Add emissions outside UK territory that can be attributed to individuals, such as international air flights, plus a pro rata proportion of emissions from international shipping: 3475 ktCO2e, not a large addition, see chart on left
  • Scope 6. Add emissions generated outside the UK but ‘embodied’ in goods consumed in the UK, per capita. This is a lot: 6503 ktCO2e, chart on right.
  • Scope 7. Add emissions in excess of average global level since 1992 when the UK signed the UNFCCC, or 2008 when the Climate Change Act came into force, or since 2015 when the UK signed the Paris Protocol. Or other dates. Difficult calculations, but possible to estimate. Much more even than Scope 6.





The whole range of ‘Russian Dolls’ is summarised in the chart below:

The range of emission scopes is very wide indeed, from 184 MtCO2e/yr to 6503 or even more, any of which has a claim to be the ‘real emissions’.

How might we ‘decarbonise’ these emissions? The County Council has limited powers, but is in control of the planning process that regulates the installation of renewable energy sources such as wind and solar electricity on a commercial scale. All it needs to do is say yes, and market forces will engage land-owners, farms and developers to do the rest.

Obviously smaller numbers (lower scope) are easier to decarbonise than large numbers, so the usual approach is to start with smaller scope and an easier problem, and explore the implications. For example, say we pick scope 1, just domestic electricity, and we wanted to replace the supply with zero-emitting sources entirely within the county. It could be done with a mixture of wind and solar, and of course there are many possible mixes. One that would ‘work’ would consist of 9 wind-farms each of 10 large 3 MW machines, plus around 40 solar farms with a total area of about 400 ha.

I can already imagine this causing apoplexy at County Hall, partly because Wiltshire is a classic ‘NIMBY’ shire county, used to getting all its goodies from outside and thereby avoiding any of the costs or conflicts. But electricity is just a small fraction of the potential total. Suppose instead we chose scope 3, all the ‘direct’ emissions from dwellings and personal surface transport. These emissions arise from energy, so we could try to ‘replace’ the fossil sources with low-energy sources. Suppose for the sake of argument we ‘electrified’ everything, electric cars, heat pumps etc, how could we generate 5314 GWh/yr of zero-carbon electricity?

One answer would be 380 wind turbines at 3 MW apiece, perhaps in ‘farms’ of 10 or so, plus 3780 MW of installed solar capacity covering a total area of 7561 ha, about 2% of the area of Wiltshire. Of course, there are other possibilities, say generating biogas from anaerobic digestors fed by dedicated fuel crops, or wood chips. These might be more appropriate than electricity for some purposes, but they would take even more land. We should bear in mind that Wiltshire has much good land for growing crops of many kinds, and some of this could be combined with conservation measures to improve biodiversity. In addition, much of the land ‘required’ by renewable energy installations is not rendered agriculturally useless and could well be used for production of stock or crops.

At this point we have only dealt with emissions from direct energy consumption, estimated at 1397 ktCO2e for the county. But the UK reports around 450 MtCO2e/yr under the Kyoto Protocol, covering all industrial sectors, investment and agriculture, and it can hardly be argued that Wiltshire does not contribute to this, or does not benefit from it. On a per capita basis this gives Wiltshire’s Scope 4 share as 3244 ktCO2e/yr.

Of course, we can try again to calculate how Wiltshire might attempt to ‘decarbonise’ this large volume of emissions, but by now it should be obvious that the matter needs to be tackled on a national, possibly international, scale. Wiltshire, like most other places, cannot achieve the feat on its own. It must rely on very large-scale operations elsewhere and pay for them. For example, very large offshore wind-power arrays produce electricity much more efficiently and cheaply, and the power is fed into the national grid. It is more rational for Wiltshire to invest in low-carbon energy where it is most easily and cheaply produced.

In a generally decarbonising world, it does not matter where the emission-reductions occur. So, yet another possibility would be for Wiltshire to invest in renewable-energy schemes in developing countries where costs are much lower. There are several institutions that exist to promote these sorts of investments. It is also possible to invest in reforestation and regeneration schemes that will absorb CO2 and ‘offset’ emissions in the UK. We can imagine Wiltshire ‘twinned’ with parts of India or Kenya or Colombia to achieve shared goals.

There is of course one other technical option, not widely favoured: nuclear power. This is generally considered a low-carbon source and it has exceptionally high power-density, so takes up less space per unit of energy generated than renewables typically do. A modern nuclear power station has an installed capacity of 2 GW and a capacity factor of 60%. It can therefore produce over 10,000 GWh of electricity a year, more than enough to meet the Scope 3 energy demand.  All this from just one power station occupying an area around 200 ha, plus around 800 ha overseas for mining and processing. The presumption would be that it is never fully decommissioned, unless the climate crisis is ‘solved’, in which case final decommissioning might be undertaken in the 22nd century. There are bound to be advocates favouring this solution, and of course it would happen within the county – although as things currently stand, the siting of nuclear power stations is not purely a county matter.

Four such power stations installed, say, on Salisbury Plain, would make Wiltshire a net exporter of enough electricity to offset emissions up to scope 6. This might sound like a reductio ad absurdum, but the grave situation demands that all options must be on the table. It is physically possible.

Failing this, to meet the demands of higher scopes, it will be necessary for Wiltshire to ‘offset’ its emissions, buying both energy and carbon emissions from outside. It still has substantial resources of land, energy and biomass to contribute to the achievement of national goals and should audit these carefully in constructing a decarbonisation strategy.

It should be noted that the building and operation of all these new power generating units will be a significant source of employment within the county.


Some readers of the above comments will be surprised that I have simply accepted the current levels of demand for energy and other carbon-emitting goods and services, and attempted to match them with the equivalent low-carbon supply. What about the possibility of reducing demand? Isn’t this more sensible?

Yes, it is more sensible, but that does not mean it is politically feasible within the county, or within the powers of the County Council.

Broadly speaking, there are two approaches to demand reduction. One is technical and largely invisible to ordinary consumers, for example changes in the Building Regulations to require more energy-efficient buildings, or rail electrification. The other is personal and involves changes of behaviour and lifestyle, for example driving less, turning down the thermostat or reducing meat consumption.

Most of the measures in both of these categories are outside the powers of the County Council. Nevertheless, we can explore them a bit. On the technical side, the thermal performance of buildings can be substantially improved by ‘retrofitted’ measures, perhaps as much as 30%. Similar gains can be made in the efficiency of vehicles. Across the whole country, reductions in emissions from industry and infrastructure are anticipated at about 2% a year, so about 20% over ten years.

What about the personal aspect? Trials with fairly detailed household-scale carbon calculators have shown that basic ‘easy’ measures like recycling waste and spending more on experiences than material goods, can reduce emissions by 10-20%. Gung-ho green-minded enthusiasts can reduce by up to 50%, but this is a very small demographic. As things stand at the moment, it would be a stretch to suggest that personal lifestyle change would make more than 20% difference over the next ten years, and the Council has little power to drive such changes.

Put the technical and personal demand reductions together, and we might have a reduction of 20-30% in the above emissions levels. This is significant, but it does not change the essential requirement for large installations of renewable energy within the county, or as an alternative, the purchase of offsets from outside.

Could we imagine something more fundamental, a dramatic shift of behaviours towards a zero-carbon Wiltshire? One key area might be food, responsible for about 25% of emissions, much of these arising from livestock production. Grassy Wiltshire has a large grazing livestock herd, and also produces intensive pork, poultry and eggs. While these are culturally an important part of the diet and have good added value, they contribute disproportionately to carbon emissions. Quick reductions of emissions can be made by switching diets away from red meat and dairy, or away from livestock products altogether. It is now well-established that a low-livestock diet is healthier and (paradoxically perhaps) leads to improved food security in the UK.

Reduction of livestock, and especially grazing, in Wiltshire frees up large areas of land for other purposes such as generating energy or growing useful non-food crops, although as noted above there is great scope for combining the production of energy and livestock in novel ways. Biomass energy produces less per unit area than wind or solar, but has the advantage of being storable. It can then be used as ‘backup’ to supply electricity when variable sources such as wind and solar cannot match demand. Such plants will be essential in a future decarbonising Britain, and Wiltshire ought to consider whether to build some. It tends to think of itself as a rural county content to buy in its energy from elsewhere, but this needs challenging. If it is to decarbonise itself in ten years it must embrace the ‘new industrialism’ implicit in renewable energy and the transformation of agricultural landscapes.

Nevertheless, changes of diet and land-use cannot make more than about 20% difference, so we are still committed to large changes in infrastructure. The question is whether we embrace these within the county, or buy them in from outside. The former of these options, which we might call WYSIWYG, bites the bullet firmly; the latter might be viewed as craven NIMBYism, but politically speaking is more likely. We might expect to find this argument advanced: if we have to operate at least partly through out-of-country procedures, why do any of it ourselves? Why not get everything from as far away as possible?


Some quick back-of-the-envelope costings

IRENA report 2017 installed costs as £0.046 per installed W for onshore wind, £0.76/W for PV. At these rates I calculate it would cost about £500M for Scope 1 installations and £4.3 billion for Scope 3, a large sum!

However, it would not all be done at once. Spread over 10 years that would be £430 million a year. But this of course generates energy, which also costs money. I estimate that Wiltshire household fuel bills are around £248 million a year, and vehicle fuels £147 million a year. Deduct these from the annual costs, and we have a small remainder of £35 million, margin of error territory. With extra carbon costs added to regular energy you can see how the whole thing might be regarded as an investment rather than a cost.

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